<template>
  <div id="calendar">
    <!-- 年份 月份 -->
    <div class="month">
      <ul>
        <!--点击会触发pickpre函数，重新刷新当前日期 @click(vue v-on:click缩写) -->
        <li class="arrow" @click="onMonth(currentYear, currentMonth)">上个月</li>
        <li class="year-month">
          <span class="choose-year">{{ currentYear }}年</span>
          <span class="choose-month">{{ currentMonth }}月</span>
        </li>
        <li class="arrow" @click="nextMonth(currentYear, currentMonth)">下个月</li>
      </ul>
    </div>
    <!-- 星期 -->
    <ul class="weekdays">
      <li>星期日</li>
      <li>星期一</li>
      <li>星期二</li>
      <li>星期三</li>
      <li>星期四</li>
      <li>星期五</li>
      <li>星期六</li>
    </ul>
    <!-- 日期 -->
    <ul class="days">
      <!-- 核心 v-for循环 每一次循环用<li>标签创建一天 -->
      <li v-for="(item, i) in days" :key="i">
        <!--本月-->
        <!--如果不是本月  改变类名加灰色-->
        <span v-if="item.day.getMonth() + 1 != currentMonth" class="other-month" @click="getDayTime(item.day)">{{ item.day.getDate() }}</span>
        <!--如果是本月  还需要判断是不是这一天-->
        <span v-else>
          <!--今天  同年同月同日-->
          <span v-if="item.day.getFullYear() == new Date().getFullYear() && item.day.getMonth() == new Date().getMonth() && item.day.getDate() == new Date().getDate()" class="active" @click="getDayTime(item.day)">{{ item.day.getDate() }}</span>
          <span v-else @click="getDayTime(item.day)">{{ item.day.getDate() }}</span>
        </span>
      </li>
    </ul>
  </div>
</template>
<script>
export default {
  data() {
    return {
      currentDay: 1,
      currentMonth: 1,
      currentYear: 1997,
      currentWeek: 1,
      days: []
    }
  },
  created: function() {
    // 在vue初始化时调用
    this.initData(null)
  },
  methods: {
    initData: function(cur) {
      // var leftcount = 0 // 存放剩余数量
      var date
      if (cur) {
        date = new Date(cur)
      } else {
        var now = new Date()
        var d = new Date(this.formatDate(now.getFullYear(), now.getMonth(), 1))
        d.setDate(35)
        date = new Date(this.formatDate(d.getFullYear(), d.getMonth() + 1, 1))
      }
      this.currentDay = date.getDate()
      this.currentYear = date.getFullYear()
      this.currentMonth = date.getMonth() + 1
      this.currentWeek = date.getDay() // 1...6,0
      if (this.currentWeek === 0) {
        this.currentWeek = 7
      }
      var str = this.formatDate(this.currentYear, this.currentMonth, this.currentDay)
      this.days.length = 0
      // 今天是周日，放在第一行第7个位置，前面6个
      // 初始化本周
      for (var i = this.currentWeek; i >= 0; i--) {
        var d2 = new Date(str)
        d2.setDate(d2.getDate() - i)
        var itemSelf = {} // 用一个对象包装Date对象  以便为以后预定功能添加属性
        itemSelf.day = d2
        this.days.push(itemSelf) // 将日期放入data 中的days数组 供页面渲染使用
      }
      // 其他周
      for (var j = 1; j <= 35 - this.currentWeek; j++) {
        var d3 = new Date(str)
        d3.setDate(d3.getDate() + j)
        var itemOther = {}
        itemOther.day = d3
        this.days.push(itemOther)
      }
    },
    getDayTime(el) {
      alert(el)
    },
    onMonth: function(year, month) {
      // setDate(0); 上月最后一天
      // setDate(-1); 上月倒数第二天
      // setDate(dx) 参数dx为 上月最后一天的前后dx天
      var d = new Date(this.formatDate(year, month, 1))
      d.setDate(0)
      this.initData(this.formatDate(d.getFullYear(), d.getMonth() + 1, 1))
    },
    nextMonth: function(year, month) {
      var d = new Date(this.formatDate(year, month, 1))
      d.setDate(35)
      this.initData(this.formatDate(d.getFullYear(), d.getMonth() + 1, 1))
    },
    // 返回 类似 2016-01-02 格式的字符串
    formatDate: function(year, month, day) {
      var y = year
      var m = month
      if (m < 10) m = '0' + m
      var d = day
      if (d < 10) d = '0' + d
      return y + '-' + m + '-' + d
    }
  }
}
</script>
<style>
#calendar {
  font-size: 12px;
  width: 100%;
  margin: 0 auto;
  box-shadow: 0 2px 2px 0 rgba(0, 0, 0, 0.14), 0 3px 1px -2px rgba(0, 0, 0, 0.1), 0 1px 5px 0 rgba(0, 0, 0, 0.12);
}
.month {
  width: 100%;
  color: #333333;
  background-color: #00b8ec;
}
.month ul {
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: space-between;
  height: 35px;
}
.year-month {
  display: flex;
  align-items: center;
  justify-content: space-around;
  margin-top: 10px;
}
.choose-month {
  text-align: center;
  font-size: 12px;
}
.arrow {
  padding: 15px;
  color: #0c0b0b;
  cursor: pointer;
  list-style: none;
}

.month ul li {
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: 3px;
}
.weekdays {
  margin: 0;
  padding: 10px;
  display: flex;
  flex-wrap: wrap;
  color: black;
  justify-content: space-around;
  background-color: #efefef;
}
.weekdays li {
  display: inline-block;
  width: 13.6%;
  text-align: center;
}
.days {
  padding: 10px;
  background: #ffffff;
  margin: 0;
  display: flex;
  flex-wrap: wrap;
  background-color: cornsilk;
}
.days li {
  list-style-type: none;
  display: inline-block;
  width: 14.2%;
  text-align: center;
  padding-bottom: 4px;
  padding-top: 10px;
  font-size: 12px;
  color: #000;
}
.days li .active {
  padding: 6px 10px;
  border-radius: 50%;
  background: #ffc0cb;
  color: #fff;
}
.days li .other-month {
  padding: 5px;
  color: gainsboro;
}
.days li:hover > span > span {
  padding: 6px 10px;
  border-radius: 50%;
  background: #e1e1e1;
  color: #fff;
}
</style>
